Born from the death of a star, stellar black holes are created by the collapsing of a star’s mass and
are the smallest form of black hole. Just as our Sun does, stars convert hydrogen into helium during nuclear ission at their core. The radiation caused by this reaction pushes against the star’s gravitational forces, which push inwards.
As long as there is a balance between the radiation and gravity, the star will remain as it is. However, as that radiation reduces over time, the ight against gravity also decreases. Eventually the gravity of the star forces its mass to fold in on itself, creating a stellar black hole, the resulting singularity around 30 or more times the mass of
our Sun. Though stellar black holes are pretty big, there are others that make them look tiny.
At the heart of galaxies are supermassive black holes. With the mass of more than 1 million Suns, these black holes are true galactic giants. While their origins are unclear, some suggest they are the result of the collapse of massive
clouds of gas during the formation of the galaxy. What is particularly interesting about supermassive black holes, and something scientist are keen to study, is its event horizon.
The point at which nothing can escape the gravitation pull of a black hole, this border casts a ‘shadow’ over the black hole. For example, using a pen, draw a circle on a piece of paper. How do you see the circle on the page? The ink is
revealing a circle, the same way as the event horizon reveals a black hole. At this point of descending ininite gravity, time itself is efected by the black hole’s gravity. Black holes, however, don’t act like a vacuum cleaner sucking up
stardust but more a deep well into which objects irretrievably fall.
Currently, the existence of a black hole as we know it is theoretical. The reason we know these masses
exist is because of the way stars and light act when one is nearby. Monitoring stars’ positions in the universe,